SIP Overlaps and Delay

Hi All,

I have 20 Cisco SPA phones logging in via SIP to a FreePBX install, which in turn has a SIP trunk to a provider.

They are using g.729 codec.

One problem we are noticing is that some users are complaining of delays and overlapping the person on the other end of the line.

It’s definitely exaggerated when dialling a mobile phone compared to a land line. Call recording is happening however i’ve disabled this for numerous extensions which reveals no change.

I was just wondering if this was a common problem. the Extensions are setup rather basically, disallow=all and allow=g729.

The connection is a 10MB Leased line of which the PBX seems to only really peak at around 40Kbps so it doesn’t look like traffic is the problem.